Is it safe to solder plastic and is it toxic?

Answer 1

Answer

If I'm a bit careless with words(there's brazing and welding too), solder is usually about joining two metal pieces together by adding a 3rd molten metal with a lower melting point where the pieces meet.

Some plastics also melt in heat, and can be used to join pieces of plastic together in a method very similar to soldering metal. It's usually done with a hot air gun with a pointy nozzle.

All types of soldering releases fumes, which are unpleasant if not outright toxic. All soldering should be done in a well-ventilated area. If you are doing lots of it, you should have a dedicated ventilation inlet righ by your work area.

Answer

By "solder" I'm presuming you mean to join using melted metal, typically for electrical conductivity (as in soldering components on a circuit board).

Since plastics, as a rule, do not conduct electricity; I'm going to guess you mean you want to solder some metal items to each other, perhaps on or through a piece of plastic.

Soldering typically involves high heat (on the order of 800 degrees Fahrenheit or more); most plastics melt or burn at such temperatures; and many plastics produce chemical fumes when heated, melted, or burned, some of which are toxic.

Another hazard of this is that molten plastic can cause serious burns on exposed skin, much like getting melted sugar on it.

I'd suggest against doing this unless you have a good reason, and do so in a well ventilated environment and protect yourself against burns if you do.